The Wireless Fidelity (Wi-Fi) Alliance published Wi-Fi direct-connecting white paper in October, 2010. Basic information, characteristics and functions about this technology are introduced in the white paper. A Wi-Fi direct-connecting standard refers to that devices in a wireless network are allowed to be connectable to one another without the need of a Wi-Fi router. Wi-Fi direct-connecting devices may be connected to one another anytime and anywhere. Due to no need of the Wi-Fi router or an Access Point (AP), the Wi-Fi devices may be connected at any places. A device discovery function and a service discovery function of Wi-Fi direct-connecting assist a user to determine available devices and service, which are then connected. Meanwhile, the Wi-Fi direct-connecting devices adopt Wi-Fi Protected Setup™, thereby simplifying a process of creating safe connection between the devices.
In a novel Wi-Fi direct-connecting network, there are two types of novel roles namely a group owner and a group client which are used to support Peer-to-Peer (P2P) connection. In a normalized definition, the group owner is compatible with a traditional Wi-Fi network and can act as a role of a Station (STA) or the AP, and in addition, P2P safe connection can be established between the group owner and multiple group clients. The group client is similar to the STA, and has functions of the STA as well as a function of establishing P2P connection with the group owner. A device may act as roles of the group owner and the group client at the same time. No matter whether traditional APs are distributed at the inner periphery of a room, a mobile terminal can be connected directly to other digital devices simply, quickly and safely by using Wi-Fi direct-connecting.
Currently, in a network structure using a Wi-Fi direct-connecting technology, a transmission rate and a connecting range are quite advantageous; meanwhile, the technology does not need to be supported by the wireless router so as to be convenient to achieve; however, the power consumption of the Wi-Fi direct-connecting technology is higher due to the problems of a transmitting power of a radio frequency antenna and the like, so that a device (terminal) adopting a direct current power supply is greatly influenced; and the Wi-Fi direct-connecting technology cannot be directly applied to the device adopting the direct current power supply.
In the traditional art, three types of 802.11 frames mainly exist. Data frames are in charge of data transmission between working stations. The data frames will be different due to different located network environments. Control frames cooperate with the data frames generally, are in charge of emptying a region, obtaining a channel and maintaining carrier sense, and give a straight answer when receiving data, thereby promoting the reliability of data transmission between the working stations. Management frames are in charge of supervision, and are mainly used to join or quit the wireless network and handle transfer events for connection between base stations.
The data frames will put data of an upper-layer protocol to a frame body for transfer. FIG. 1 shows a basic structure of each data frame.
The control frames mainly assist the data frames in transfer. They can be used to supervise access of a wireless medium (but not the medium itself), and provide the reliability of a Media Access Control (MAC) level.
As shown in FIG. 2, the control frames have the same frame control bit.
FIG. 3 shows a basic structure of each management frame. MAC headers of all the management frames are the same, which is irrelevant to sub-types of the frames. The management frames will exchange the data with other systems by using information elements (data blocks with digital tags).
According to a theoretical value, under the conditions that it is tested that an 11M rate of an 802.11b and a transmitting power (16 dbm generally) are certain, it is calculated that power consumed for receiving the data in unit time 100 ms is 410 mw and power consumed for sending the data is 500 mw. Meanwhile, by means of an actual network throughput (6M/s), it can be calculated that power consumed for receiving unit data 1 kbit is 0.68 mw and power consumed for sending the unit data 1 kbit is 0.83 mw.